胃癌診断におけるルーチン検査の確かさ―集団検診からみて

Precision of Routine Examination in the Gastric Carcinoma Mass Survey

要旨　X線，内視鏡を使っての胃癌の診断は飛躍的進歩を遂げ2～3mmの微小胃癌の発見も可能になってきているが，一方，大きな進行癌が見逃されることもそう少ない経験ではない．そこで，今回胃集検における間接X線診断の精度を検討し，今後の改善の方向性を考えてみた．1970～1982年度の北海道対がん協会の胃集検，総受診数1,644,658，発見癌2,017を対象としaccidentally detected cancer法（以下ADC法）により偽陰性率を算出すると，合計で29.7％，X線無示現が要因のもの14.8％，読み落としが要因のもの10.4％であった．更に胃癌の部位，大きさ別に検討すると，胃上部・後壁・大彎で無示現，読み落としとも多く，小病変で無示現が多かった．これらの病変を更に良く現す撮影法の改善と，double readingなど読み落としを減少させる読影の工夫が必要と思われた．

　Although it has become possible to detect minute gastric carcinoma (2-3mm in diameter) due to rapid progress in the diagnosis of stomach cancer, namely by using radiography and endoscopy in close examinations, many cases of advanced carcinoma go unnoticed. The diagnostic accuracy of photofluorography in the gastric carcinoma mass survey, as well as future dimensions in accuracy improvement was considered.

　The total number of examinees in the gastric carcinoma mass survey program that was conducted by the Hokkaido Cancer Society during the period 1970-1982 was 1,644,658, of which 2,017 cases of gastric carcinoma were detected. False-negative rate (FNR) was estimated by using the “accidentally detected carcinoma” (ADC) method. The overall FNRs for this program was estimated at 29.7%, including 14.8 of x-ray “shadows-not-detected” and 10.4% of “readingfailure”. As a result of studies of carcinoma according to its affected region and size, many cases of “shadows-not-detected” and “reading failure” were found to have occurred at C, Post and Maj (Fig. 5); many cases of “failure-not-detected” were found for minor lesions. An improvement in photograph, which can clearly depict lesions, as well as careful re-reading which prevents reading failure, are of great necessity.